There is a slight problem currently facing which is the mobo has insufficient power ... i am setting up a 8 card and the board is givin in.

But even with powered risers? I was thinking the same but then bought on aliexpress some m2 to pciex adapters that have auxiliary power. I saw the article on nicehash blog and thought that 9 gpu could be possible.

8 cards on MSI Z270A-Pro w/ PCI-e splitter works fine, never even bothered with the M2

Which spliter do you use?

The splitters from every vendor are pretty much the same. Look for Ver. 4 on the PCB

A cautionary warning tho, if you use splitters you increase the risk of these burning out and shorting both your GPUs and boards.There are lots of horror stories here and around the net about burn outs. Make sure you know what you are doing (get the right power supply, connect mobo to only 1 psu, etc.)

So if you have a mobo with 7 pci you can have 21 gpus at the same time with enough power supplies attached?

No, if you have 1x 16x PCI-Express means (I think) you can connect in it 16 devices. Now plug in that 16x PCI-E one Switch PCI-E Multiplier, in that multiplier, you put another 3, resulting 9. I am not sure this will work, as the multipliers may or may be not suitable for such things. On the 1x PCI-E you can put only one videocard, the switch won't help, place the switches in 16x PCI-E, that's what I did.

No, if you have 1x 16x PCI-Express means (I think) you can connect in it 16 devices. Now plug in that 16x PCI-E one Switch PCI-E Multiplier, in that multiplier, you put another 3, resulting 9. I am not sure this will work, as the multipliers may or may be not suitable for such things. On the 1x PCI-E you can put only one videocard, the switch won't help, place the switches in 16x PCI-E, that's what I did.

I'm currently using this mobo and trying to setup a 6 GPU rig but I'm having problems getting the motherboard to boot with 5 GPUs. It shows al the GPUs plugged into the motherboard but in the device manager it is telling me that 3 of the 5 are not working properly because there are not enough resources (code 12). I'm not sure what I need to set it the bios to allow this. Any advice? Screenshots of bios config? Thanks

I am running two rigs with this board using 6 gpus sucessfully and soon to test with 7.

I can tell you that you won't be able to use both of the M.2 slots as you hoped because atleast 1 of the M.2 slots shared PCIe lanes with the PCIex1 #2 and #4 slots on the motherboard. I know this because to get 6 gpu's to run correctly you have to distinctly change that setting to disable the M.2 slot in bios and use the PCIex1 #2,4 instead. I am not positive but you may be able to use the other M.2 slot. I will double check, if so I may just order an adapter and try it out.

I am running two rigs with this board using 6 gpus sucessfully and soon to test with 7.

I can tell you that you won't be able to use both of the M.2 slots as you hoped because atleast 1 of the M.2 slots shared PCIe lanes with the PCIex1 #2 and #4 slots on the motherboard. I know this because to get 6 gpu's to run correctly you have to distinctly change that setting to disable the M.2 slot in bios and use the PCIex1 #2,4 instead. I am not positive but you may be able to use the other M.2 slot. I will double check, if so I may just order an adapter and try it out.